JPH07140954A - Image synthesizer - Google Patents

Abstract

PURPOSE:To provide an image synthesizer capable of syntheizing plural systems of images whose pixel aspect ratios are different from each other and displaying pictures with aspect ratios required by respective images. CONSTITUTION:This device is provided with an aspect ratio conversion means 4 converting 15 dots in the horizontal direction to 14 dots for the moving image data 3a of e.g. horizontal 711, vertical 487 dots (aspect ratio 4:3 of a reproducing picture and aspect ratio 1.072 of a reproducing pixel are assumed) outputted from a moving image reproducing device 3. The device is provided with a synthesis means 5 selecting either one side between the image data 10a delaying the computer image data 2a of e.g. horizontal 640, vertical 480 dots (pixel aspect ratio 1) outputted from a computer image reproducing device 2 and the aspect ratio converted moving image data 4a based on synthesis range specifying information 5b and generating an image synthesis output 5a, and the image synthesis output 5a is converted into an analog video signal 6a by a D/A converter 6, and a synthesis image is reproduced on a monitor display device 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention assumes that the aspect ratio of pixels of a reproduced image is other than 1: 1, for example, moving image data of the MPEG system and the aspect ratio of pixels of a reproduced image is 1: 1. The present invention relates to an image synthesizing device capable of synthesizing images assuming different pixel aspect ratios and synthesizing images with the intended aspect ratio on the same screen when synthesizing computer image data with each other. .

[0002]

2. Description of the Related Art In recent years, devices for handling images have been digitized. There are roughly two types of devices that handle images. One is a device related to broadcasting represented by television and video, and the other is a computer. They have different histories and have grown under completely separate standards. In recent years, technological advances have made it possible to develop devices that combine these devices at the consumer level.
However, from the background of their growth, these are image formats based on completely different standards, and it was essential for the two fusion to absorb the difference between these standards.

The most typical digital standard represented by broadcasting is a standard called CCIR REC601. This standard defines the luminance signal Y as the pixel rate 13.
Basically, the signal is sampled at 5 MHz and the color difference signals Cb and Cr are sampled at 6.25 MHz, which is half of the signal. When this is applied to the broadcasting standard of NTSC,
711 dots in width and 487 dots in height will be displayed on the screen with an aspect ratio of 4: 3 (aspect ratio of the reproduced image), and the aspect ratio of each pixel of the reproduced image (hereinafter referred to as pixel aspect ratio) is a vertically long image. 1.095 = {(3 ÷ 487) / (4 ÷ 7
11)}. This is a case of displaying on a normal NTSC television by interlace overscan.

On the other hand, the computer is usually VGA (VI
When underscan is displayed on the monitor of DEO GRAPHICS ARRAY), the pixel rate is 25.
At 175 MHz, 640 horizontal dots and 480 vertical dots will be displayed on the screen with an aspect ratio (aspect ratio of the reproduced image) of 4: 3, and the pixel aspect ratio will be 1.0 = {(3/48
0) / (4/640)} and square pixels. In addition, when reproducing the image of the computer on the television of the NTSC system, 1.095 ÷ (13.5MHz ×
(2 ÷ 25.175 MHz) = 1.021 pixel aspect ratio. Further, when an image of REC601 standard is displayed on the monitor display of the computer, the pixel aspect ratio becomes 1.095 / 1.021 = 1.072. The above is summarized in Table 1.

[0005]

[Table 1]

Conventionally, in a device that fuses these, since these are reproduced by the clock of the same computer side,
Originally, there was a drawback that the picture of the moving image made by the standard for broadcasting was displayed in landscape.

FIG. 4 is a block diagram of a conventional image synthesizing apparatus. The conventional image compositing apparatus 100 assumes a computer monitor as the monitor display device 106. The moving image reproducing apparatus 101 sequentially outputs the image data 101a of each pixel in synchronization with the 25.175 MHz reference clock MCK supplied from the reference clock generation circuit 102. The output of this image data 101a is 27M.
Since it was originally created for REC 601 that outputs at a frequency of 0.1 Hz, it corresponds to the lower right column of Table 1 and has a pixel aspect ratio of 1.
072 is assumed. This is actually 2
When outputting at 5.175 MHz, the pixel aspect ratio becomes 1.0, and as a result, what should be displayed with the pixel aspect ratio of 1.072 is displayed with 1.0. This means that it looks wider than it should be, and the error is 0.932 (= 1.0 / 1.072 = 2) in terms of ratio.
5.172 / 27), which is 7%. On the other hand, the computer image reproducing device 103 sequentially outputs the image data 103a of each pixel assuming a pixel aspect ratio of 1.0 in synchronization with the reference clock MCK.
This looks normal because it was originally created with a pixel aspect ratio of 1.0 and displayed with 1.0. Image synthesizer 1
04 selects one of the image data 101a and 103a based on the synthesis range designation information 104b and supplies it to the D / A converter 105. The analog video signal 105a output from the D / A converter 105 is supplied to the monitor display device 106 of the computer for image reproduction.

[0008]

However, the conventional image synthesizing apparatus 100 simply selects and switches two types of image data having different assumed pixel aspect ratios and synthesizes them. Therefore, the combined image data 10
4a is displayed on the monitor display device 106 of the computer, the screen from the moving image reproducing device 101 is 7
It looks like percent horizontal. In general, the human eye notices the difference when the ratio of the errors exceeds 3%, and feels that the aspect ratio of the reproduced image is wrong.

The present invention has been made in order to solve the above problems, and performs aspect ratio conversion on the moving image side to reproduce and display a composite image of the moving image and the computer image in the originally intended picture state. It is an object of the present invention to provide an image reproducing device capable of performing the above.

[0010]

In order to solve the above-mentioned problems, an image synthesizing device according to the present invention is a device for synthesizing a moving image and a computer image so that they are mixedly displayed on the same screen. It is characterized by comprising an aspect ratio conversion means for performing aspect conversion and an image composition means for composing a moving image and a computer image subjected to aspect ratio conversion.

The aspect ratio conversion means is 1 in the horizontal direction.
A configuration in which 5 dots are converted to 14 dots is preferable.

[0012]

The aspect ratio conversion circuit changes the aspect ratio of the reproduced image when the aspect ratio of the reproduced pixel assumed by the moving image is displayed in an aspect ratio close to the aspect ratio of the reproduced pixel assumed by the computer image. Aspect ratio conversion is performed so that the aspect ratio is substantially equal to the aspect ratio of the original image, and the image data for each pixel that has undergone the aspect ratio conversion is output. Therefore, by selectively switching between the aspect-converted moving image data and computer image data and combining and displaying two types of images, a picture with the aspect ratio originally intended for the moving image is combined and displayed.

It should be noted that 15 dots in the horizontal direction of a moving image are converted into 14 dots.
By using the aspect ratio conversion unit configured to convert to dots, for example, image data of 711 horizontal dots and 487 vertical dots with a screen aspect ratio of 4: 3 defined by the CCIR REC601 standard (pixel aspect ratio 1. 072) can be converted into image data having a screen aspect ratio of 4: 3 and horizontal 664 dots and vertical 487 dots (pixel aspect ratio 1.001). In this case, the aspect ratio conversion means has a relatively simple structure of converting from 15 dots to 14 dots, but the error of the aspect ratio with respect to the pixel aspect ratio of 1.0 assumed by the computer image side is only 0.1%. And does not cause any visual problem.

When the aspect ratio of a pixel is converted, the error changes depending on the ratio. When converting a REC601 standard moving image into a computer image assuming a pixel aspect ratio of 1.0 (square pixels), the ratio to be converted is 27 / 25.175 = 1.072. Assuming that N is converted to M, the optimum M and error for N are determined for each natural number. Specifically, when 1.072 × N / M> 1, it is defined by this, and when 1.072 × N / M <1, it is defined by its reciprocal. Table 2 shows the optimum M and the error for each N. It can be seen from Table 2 that the minimum value of the error appears in a certain fixed period.

[0015]

[Table 2]

As described above, since the human eye can tolerate the deviation of the aspect ratio if the error is within 3 percent, if N is 11 or more, the error within 3 percent is satisfied. If N is set large, the error can be reduced, but if N is large, the hardware and software configurations for aspect ratio conversion become complicated. So N
Is 11 or more, the error first becomes small N = 15, M = 1
By adopting 4, the error can be reduced without complicating the hardware configuration. When N = 15 and M = 14, the error is 0.1%, and the error of 0.1% does not cause any problem in human visual characteristics.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block configuration diagram of an image synthesizing apparatus according to the present invention. In this case as well, the monitor display device 7 is assumed to be a computer monitor. This image synthesizing device 1 is a computer image reproducing device 2 which outputs computer image data 2a of 640 dots in the horizontal direction and 480 dots in the vertical direction, for example, assuming that the aspect ratio of the reproduced image is 4: 3 and the pixel aspect ratio is 1.0. Assuming an image aspect ratio of 4: 3 and a pixel aspect ratio of 1.072, for example, horizontal 711 dots, vertical 487 dots (CCIR RE
It comprises a moving image reproducing apparatus 3 which outputs moving image data 3a of C601 standard), an aspect ratio converting unit 4 which converts 15 dots in the horizontal direction into 14 dots, and an image synthesizing unit 5.

The composite image data output 5a of the image composition means 5
Is converted into an analog video signal 6a by the D / A converter 6 and supplied to the monitor display device 7 of the computer.
An image is reproduced on the screen of the monitor display device 7.

The reference clock MCK having a frequency of 25.175 MHz generated by the reference clock generating circuit 8 having a crystal oscillator or the like is supplied to the computer image reproducing apparatus 2. The computer image reproducing device 2 outputs the image data 2a of each pixel in a preset pixel order (for example, non-interlace) in synchronization with the reference clock MCK.

The PLL circuit 9 has a frequency of 25.175 MH.
With the reference clock MCK of z as the input, the frequency 27 MHz that is (858/800) times this reference clock MCK.
Video playback clock 9a synchronized with the reference clock
Is generated and supplied to the moving image reproducing apparatus 3.

The moving image reproducing apparatus 3 synchronizes with the moving image reproducing clock 9a having a frequency of 27 MHz and the image data 3 of each pixel in a preset pixel order (for example, non-interlaced).
Output a.

FIG. 2 is a block diagram showing a specific example of the aspect ratio converting means, and FIG. 3 is an explanatory diagram showing the operation of the aspect ratio converting means. Reference numeral 41 shown in FIG. 2 is an aspect ratio converter, which operates as shown in FIG. Reference numeral 42
Is a FIFO (temporary first-in first-out image data storage means), which is written by the FIFO write controller 43 and is read by the FIFO read controller 4
4 is read. FIG. 3 shows the aspect ratio converter 4
The operation timing is 1 and data is sequentially sent from the moving image reproducing apparatus 3 from Y0 every 27 MHz. The aspect conversion unit 41 performs linear interpolation calculation as shown in the calculation column. FIG. 3 shows 15 conversion tables, which are repeated. At the start of this conversion, a start signal 41a is output to the FIFO write control unit 43, and the FIFO write control unit 43 outputs the FIFO signal of FIG.
As shown in the write column, 14 pieces of data counted from there are written to the FIFO 42, and 1 piece of data is written to the FIFO.
Aspect conversion of 15:14 is performed without writing to O42. The FIFO read control unit 44 reads the data from the FIFO 42 so as to be sent to the image synthesizing means 5 in synchronization with the data from the computer image reproducing apparatus 2.

The image synthesizing means 5 shown in FIG. 1 delays the aspect ratio-converted image data 4a or the image data 2a output from the computer image reproducing apparatus 2 by the delay means 10.
Any one of the image data 10a delayed via the above is selected and output in synchronization with the reference clock MCK. The synthesis range designation information 5b indicating which range is to be selected for each image is supplied from a synthesis range designation means (not shown).

The delay means 10 provided between the computer image reproducing device 2 and the image synthesizing means 5 delays the transmission of the computer image data 2a by the time required for aspect-converting the moving image data 3a. The delayed computer image data 10a is output, and is configured by, for example, a temporary storage unit having a first-in first-out (FIFO) configuration.

With the above configuration, the moving image reproducing apparatus 3
711 dots horizontal and 487 dots vertical moving image data 3a assuming a pixel aspect ratio of 1.072 output from
Is converted into moving image data 4a corresponding to a pixel aspect ratio of 1.001 when displayed at an aspect ratio of 4: 3 in a reproduction screen with 664 dots in the horizontal direction and 487 dots in the vertical direction through the aspect ratio conversion means 4. It is supplied to the image synthesizing means 5. Therefore, the image synthesizing unit 5 uses the synthesis range designation information 5
The image composite data output 5a can be generated by selecting and outputting either one of the two systems of image data 10a and 4a based on b.

The image synthesis data output 5a output from the image synthesis means 5 in synchronization with the reference clock MCK is converted into an analog video signal 6a by the D / A converter 6 and reproduced by the monitor display device 7. The moving image data 3a, which is output from the moving image reproducing apparatus 3 and assumes the pixel aspect ratio of 1.072, has a pixel aspect ratio of 1.0 assumed by the computer image reproducing apparatus 2 via the aspect ratio conversion means 4. Closer pixel aspect ratio 1.001
After the aspect conversion is performed on the image data 4a, the image is synthesized by the image synthesizing unit 5, so that the synthesized image of each image is reproduced based on the originally intended aspect ratio.

[0027]

As described above, the image synthesizing apparatus according to the present invention uses the aspect ratio of the reproduced pixels assumed by the moving image to approximate the aspect ratio of the reproduced pixels assumed by the computer image. Aspect ratio conversion is performed so that the aspect ratio of the reproduced image when displayed is approximately equal to the aspect ratio of the original image, and the moving image and the computer image that have undergone the aspect ratio conversion are combined by the image combining means and displayed. The composite image of each image can be reproduced based on the aspect ratio originally intended for each image. Since the image composition is performed after aspect conversion so that the pixel aspect ratios of the respective images are almost equal, the image composition means only needs to select which image data of each pixel should be taken. The configuration can be simplified.

By using the aspect ratio converting means configured to convert 15 dots into 14 dots, for example, it is defined by the CCIR REC601 standard.
Image data of 711 horizontal dots and 487 vertical dots with a screen aspect ratio of 4: 3 (pixel aspect ratio 1.072 when displayed on a computer monitor) is displayed with a screen aspect ratio of 4: 3 horizontal dots and 487 vertical dots. It can be converted into image data (pixel aspect ratio 1.001). In this case, since the aspect ratio conversion means has a relatively simple structure of converting 15 dots to 14 dots, the aspect ratio conversion means can be realized at a low cost with a simple structure. Further, the error of the aspect ratio with respect to the pixel aspect ratio of 1.0 assumed by the computer image side is only 0.1 percent, and causes no visual problem.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an image synthesizing apparatus according to the present invention.

FIG. 2 is a block diagram showing a specific example of an aspect ratio conversion unit.

FIG. 3 is an explanatory diagram showing the operation of the aspect ratio conversion means.

FIG. 4 is a block configuration diagram of a conventional image synthesizing device.

[Explanation of symbols]

1 ... Image synthesizing device, 2 ... Computer image reproducing device, 2
a ... Computer image data, 3 ... moving image reproducing device, 3
a ... moving image data, 4 ... aspect ratio conversion means, 4a ...
Aspect ratio converted moving image data, 5 ... Image synthesizing means, 5a ... Image synthesized data output, 6 ... D / A converter, 7
... monitor display device, 8 ... reference clock generation circuit, 9 ... PLL circuit, 10 ... delay means, 10a ... delayed computer image data, 41 ... aspect ratio conversion section, 41a ... start signal, 42 ... FIFO (first-in-first) Out-structured image data temporary storage means), 43 ... FIFO write control unit, 44 ... FIFO
Read control unit.

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Claims (2)

[Claims] 1. An image synthesizing apparatus for synthesizing a specified range of each image in order to display a moving image and a computer image in a mixed manner on the same screen. Aspect ratio conversion for performing aspect ratio conversion on the moving image. An image synthesizing apparatus comprising: a means and an image synthesizing means for generating a synthesized image by selecting one of a moving image subjected to aspect ratio conversion and a computer image. 2. The aspect ratio conversion means is 1 in the horizontal direction.
The image synthesizing apparatus according to claim 1, wherein 5 dots are converted into 14 dots.